It is common to employ aluminum or aluminum alloy as the substrate material of electrostatographic imaging members due to the lower cost of aluminum or aluminum alloy as compared with for example a nickel substrate. A known technique for creating a charge blocking layer on the substrate is by anodizing the surface of the aluminum substrate to create a layer of aluminum oxide. There is a need, which the present invention addresses, to expand the design parameters for imaging members by allowing different combinations of materials to be used for the substrate and the metal oxide layer functioning as the charge blocking layer. Such a blocking layer then allows subsequent layers to perform a single function such as adhesion or suppression of light interference fringes rather than having to provide dual functions which often result in a design compromise.
The following patents disclose conventional imaging members: Fukuda et al., U.S. Pat. No. 5,219,691; Andrews et al., U.S. Pat. No. 5,215,853; Yuh et al., U.S. Pat. No. 5,654,118; Yuh et al, U.S. Pat. No. 5,532,093; and Ueda et al., U.S. Pat. No. 4,800,144.